1. Field of the Invention
The present invention relates to an antenna unit, and in particular relates to an antenna unit with improved isolation and beamwidth. The disclosed antenna unit is suitable for use in a phased-array antenna.
2. Description of the Related Art
FIG. 1 shows a conventional antenna 1, including an antenna substrate 10, a feed substrate 20, a microstrip patch 30, a ground plane 40 and a microstrip feed line 50. The antenna substrate 10 includes a first surface 11 and a second surface 12. The feed substrate 20 includes a third surface 21 and a fourth surface 22. The microstrip patch 30 is disposed on the first surface 11. The ground plane 40 is disposed on the third surface 21. The second surface 12 is connected to the ground plane 40. A coupling aperture 41 is formed on the ground plane 40. The microstrip feed line 50 is disposed on the fourth surface 22. The microstrip feed line 50 feeds wireless signals via the coupling aperture 41 to the microstrip patch 30. Conventional antennas typically have small bandwidths, undesirable back radiation and unwanted surface wave radiation issues. Additionally, when the conventional antennas are arranged in an array, isolation between the antennas is poor. c